1. Field of the Invention
The present invention relates to an oxidatively carbonatable composition, a oxidatively carbonatable paste, a method of using an oxidatively carbonatable composition, an oxidatively carbonated composition, a method of making an oxidatively carbonated composition, and an article formed from the oxidatively carbonated composition.
2. Discussion of the Background
Mixing fine iron powder particles with water and chloride salts forms a paste that corrodes when exposed to air. On the surface of the paste, the oxidative process oxidizes the iron to form an orange and brown coating commonly known as rust.
Deeper within the paste, away from the surface, oxygen is more limited. Because of the limited oxygen deep within the paste, metallic iron atoms lose both three and two electrons to form ferric and ferrous ions, respectively. This combination of different iron ions with different charges, known as a mixed valence, forms, with oxygen, Fe2+1Fe3+2O4 or Fe3O4, found in nature as the mineral magnetite.
In magnetite, the oxygen atoms are shared between the ferric and ferrous ions by bridging. The magnetite forms a hard, continuous, inter-bonded matrix and the iron particles become effectively cemented together, thus forming one kind of iron cement.
The process of making the above-described iron cement has been known for over a century, and the magnetite iron cement resulting from the process is very strong.
Attesting to the strength of the cement, in 1885, the trade journal The Manufacturer and Builder reported that a mixture of iron filings, chloride salts, and water produced a cemented joint between two pipe flanges so strong that when bent and broken apart the next day, one of the cast iron flanges failed before the newly formed cement joint split.
However, the above described form of iron cement has drawbacks. Using such a large amount of iron to form a cement is expensive. Additionally, the mixing of such a paste on a large scale can be difficult.
Thus, while iron cements are useful, a need exists for an improved composition that employs less iron than the iron cement that forms magnetite, is more workable in the paste form on large scale, is less expensive to make, and can form a strong inter-bonded matrix. This composition is also important for its ability to permanently trap CO2, utilize industrial waste products, and sequester toxic contaminants such as arsenic and heavy metals like lead.